Backend Engineer - Databases and APIs in City of Westminster

We are looking for a Backend Engineer to lead our API and database development. In this role, you will own the data layer that powers our platform. This role sits at the intersection of data architecture and backend engineering. You will define how data flows from external sources into our systems, how it is stored, transformed, and optimised, and how it is ultimately served through performant, reliable APIs. You will build the foundations that enable scalable data ingestion, consistent modelling, and fast access across diverse data types. This is a full‑time role based in London on a hybrid working pattern (2–3 days per week in the office).

You will work closely with product, data, and engineering teams to build resilient pipelines, coherent data models, and scalable backend services that support a wide variety of use cases across the organisation. Your work will directly influence platform performance, data integrity, and our ability to make informed, data‑driven decisions.

Key responsibilities are to:

• Design and implement database schemas optimised for time‑series, geospatial, multimedia, and relational data.
• Build robust data‑integration pipelines that ingest from multiple third‑party APIs, handling inconsistencies, failures, and schema changes.
• Develop and optimise API endpoints using Python and FastAPI to serve data efficiently and reliably at scale.
• Implement caching strategies, materialised views, and denormalisation patterns to maintain responsive query performance.
• Design coherent data models that reconcile disparate data sources into a unified internal schema.
• Manage core database operations including migrations, indexing strategies, query optimisation, and performance monitoring.
• Build resilient ETL processes with strong error handling, retry logic, and validation mechanisms.
• Deploy and maintain data infrastructure on AWS, including RDS, Redis, S3, and MongoDB where required.

What you bring (knowledge, expertise, experience, and skills):

Essential:

• 3–5 years’ experience in backend development with a strong focus on databases.
• Deep expertise in PostgreSQL, including schema design, indexing, query optimisation, and stored procedures.
• Strong proficiency in Python, with hands‑on experience using FastAPI or similar frameworks.
• Experience designing data models for complex, multi‑source systems.
• Hands‑on experience building large‑scale integrations with third‑party APIs.
• Solid understanding of data consistency, transactions, and failure‑handling patterns.
• Experience with AWS data services (RDS, S3, MongoDB, Redis).
• Strong SQL skills and the ability to write efficient queries on large datasets.
• Familiarity with AI‑assisted development tools (e.g., Claude Code, GitHub Copilot).

Desirable:

• Experience with specialist database extensions such as PostGIS (geospatial), TimescaleDB (time‑series), or pgvector (embeddings).
• Background with NoSQL databases (e.g., DynamoDB, MongoDB) and an understanding of when to apply them.
• Experience with data warehousing concepts and analytical query patterns.
• Familiarity with message queues and event‑driven architectures for data pipelines.
• Experience with database replication, partitioning, and high‑availability configurations.

What you get:

A competitive salary and benefits package that includes 27 days holiday per year, pension contributions, private healthcare, discounted dental insurance, enhanced maternity/parental leave, plus a whole host of others including:

• Cultural stimulation allowance - £250 per person per year
• Half days off before bank holidays
• Emergency care days for dependants
• Up to 5 days volunteering leave per year to work for a registered charity
• Up to 10 days special emergency leave per year
• Season Ticket loan
• Payroll Giving Scheme
• Thursday drinks to unwind and socialise
• An annual Summer and Christmas party

Our commitment to Diversity and Inclusion sees us offer inclusive bank holidays. We also offer learning opportunities around D&I, targeted mentoring programmes and the opportunity to participate in several active Employee Led Networks and associated events. Finally, this role will be supported with all the necessary personal development required to set someone up for success.

M+C Saatchi World Services is a specialist division of M+C Saatchi Group, the world’s largest independent communications network. Our specialists work in office hubs across six continents, grounding our global expertise in local nuance. We offer award-winning commercial communications capabilities, which are utilized by global organizations to address the world’s most complex problems across defence, development, diplomacy, homeland and national security, law and order, health, education, and the environment. We work with clients that want to help the hardest-to-reach, hardest-to-influence audiences. This includes a range of Western Government departments, such as DOS and USAID; partner governments, including the U.K. and Australia; and prominent IGOs/NGOs such as the U.N. We are a comms agency that works on behaviour change projects typically focused on issues related to Security, Defence and Stabilization.